Method for manufacturing organic EL display and organic EL display

ABSTRACT

Disclosed herein is a method for manufacturing an organic electroluminescence display including multilayer structures that are each formed in a respective one of pixel areas in an effective area of a substrate and are each formed by a lower electrode, an organic layer, and an upper electrode, the organic electroluminescence display having a common electrode that electrically connects the pixel areas, the method including the steps of: forming a protective electrode and an outer-peripheral electrode that are electrically connected to the common electrode; forming the multilayer structures; and carrying out film deposition treatment involving electrification of the substrate.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2007-177992 filed in the Japan Patent Office on Jul. 6,2007, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing an organicelectroluminescence (EL) display including organic EL elements and anorganic EL display obtained by the manufacturing method.

2. Description of the Related Art

In recent years, organic EL displays including organic EL elements aslight-emitting elements are attracting attention as flat displays. Theorganic EL display is a self-luminous flat panel display that demands nobacklight, and has an advantage that it can realize a display with awide viewing angle, which is a characteristic of the self-luminousdisplay. Furthermore, the organic EL display is advantageous overbacklight-type displays (such as liquid crystal displays) in the powerconsumption because only the necessary pixels are turned to thelight-emission state in the organic EL display. In addition, the organicEL display is considered to have sufficient response performance withrespect to high-definition and high-speed video signals that areexpected to be put into practical use in the future.

In a general organic EL display, a lower electrode serving as a positiveelectrode (anode) is formed over a substrate formed of e.g. a glasspanel. On the lower electrode, an organic layer composed of a holetransport layer and a light-emitting layer is formed. On the organiclayer, an upper electrode serving as a negative electrode (cathode) isformed. Based on this structure, an organic EL element is formed at eachposition at which the lower electrode, the organic layer, and the upperelectrode overlap with each other. A light-emission area is formed byvertically and horizontally arranging these organic EL elements. In aperipheral area thereof, an electrode portion for connecting therespective organic EL elements to an external circuit or internal drivecircuit is formed (refer to e.g. Japanese Patent Laid-Open No.2004-207217 and Japanese Patent Laid-Open No. 2004-139970).

For the general organic EL display having such a structure, as shown inFIG. 19 for example, an area 54 outside an effective area 53 (areacomposed of a light-emission area 51 and a peripheral area 52 thereof)on the substrate is removed (along the cut lines in FIG. 19) after thefilm deposition of the respective layers, so that the organic EL displayis completed. In this case, the effective area 53 and the other area 54are not electrically connected to each other in general.

SUMMARY OF THE INVENTION

The organic EL display is manufactured by using various film depositiontechniques, specifically publicly-known vacuum evaporation techniquesand chemical vapor deposition (CVD) techniques. For example, after thestep of forming the organic EL elements and before the step of leavingonly the effective area 53, a silicon nitride (SiN) film covering theentire substrate including the organic EL elements is formed as aprotective film for protecting the entire substrate by CVD depositiontreatment involving electrification.

However, in a related-art manufacturing process for an organic ELdisplay, a part that looks white turbidity is possibly generated in thevicinity of the outer periphery of the light-emission area 51 attributedto e.g. an electrification charge arising due to plasma generation inthe CVD deposition treatment. This phenomenon is due to the possibilitythat a potential difference arises between the effective area 53 and theother area 54 attributed to the plasma generation in the CVD depositiontreatment and this potential difference precludes the protective filmfrom being uniformly formed by the CVD deposition treatment.Specifically, the electrification charge of the protective filmaccumulates in the vicinity of the outer periphery of the light-emissionarea 51 attributed to the potential difference in the plane of thelight-emission area 51. This charge accumulation causes film rougheningon the surface of the protective film, and this film roughening lookswhite turbidity. Furthermore, the plasma generation possibly imposeselectric damage on electric circuits such as a thin film transistor(hereinafter, referred to as a “TFT”) circuit included in the organic ELdisplay.

There is a need for the present invention to provide an improved methodfor manufacturing an organic EL display, allowing suppression of theadverse effect of an electrification charge that is possibly generatedin film deposition treatment in the manufacturing process, and toprovide an organic EL display manufactured by the method.

According to an embodiment of the present invention, there is provided amethod for manufacturing an organic EL display including multilayerstructures that are each formed in a respective one of pixel areas in aneffective area of a substrate and are each formed by a lower electrode,an organic layer, and an upper electrode. The organic EL display has acommon electrode that electrically connects the pixel areas. The methodincludes the steps of forming a protective electrode and anouter-peripheral electrode that are electrically connected to the commonelectrode, forming the multilayer structures, and carrying out filmdeposition treatment involving electrification of the substrate.

In the method for manufacturing an organic EL display based on thisconfiguration, the protective electrode that is electrically connectedto the common electrode and the outer-peripheral electrode are formedbefore the film deposition treatment involving electrification of thesubstrate. Therefore, even when a film is charged in the film depositiontreatment, the electrification charge flows toward the outside of theeffective area due to a charge flow to the protective electrode and theouter-peripheral electrode. This avoids the occurrence of accumulationof the electrification charge at a certain position in the effectivearea.

According to the embodiment of the present invention, the accumulationof the electrification charge at a certain position in the effectivearea is avoided. Therefore, even if film deposition treatment involvingelectrification such as CVD deposition by use of plasma treatment iscarried out in the manufacturing process for an organic EL display, itis possible to suppress generation of white turbidity at a certainposition in the effective area attributed to the electrification chargegenerated in the film deposition treatment. Moreover, the charge flowtoward the outside of the effective area can also avoid electric damageto electric circuits included in the organic EL display. Consequently,an organic EL display free from the occurrence of white turbidity andelectric damage can be manufactured, which allows enhancement in themanufacturing quality, manufacturing yield, and so forth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a major-part sectional view showing one example of theschematic structure of a display area of an organic EL display;

FIGS. 2A to 2F are explanatory diagrams showing one example ofmanufacturing steps for the organic EL display;

FIG. 3 is a perspective view showing a schematic configuration exampleof the organic EL display;

FIG. 4 is an explanatory diagram showing one example of a manufacturingstep for an organic EL display according to a first embodiment of thepresent invention;

FIGS. 5A to 5C are explanatory diagrams showing specific examples of theformation positions of protective electrodes;

FIG. 6 is an explanatory diagram showing another example of amanufacturing step for an organic EL display according to a secondembodiment of the present invention;

FIG. 7 is a perspective view showing another schematic configurationexample of the organic EL display;

FIG. 8 is a major-part sectional view showing another example of theschematic structure of a display area of an organic EL display;

FIG. 9 is a circuit diagram schematically showing a specific example ofinterconnects in an effective area of an organic EL display;

FIG. 10 is a circuit diagram schematically showing a connection examplein which an upper-electrode interconnect is used as a common electrode;

FIG. 11 is a circuit diagram schematically showing a modificationexample in which the upper-electrode interconnect is used as a commonelectrode;

FIG. 12 is a circuit diagram schematically showing a connection examplein which a power supply line is used as a common electrode;

FIG. 13 is a circuit diagram schematically showing a connection examplein which signal lines are used as a common electrode;

FIG. 14 is a perspective view showing a television as one specificexample of electronic apparatus;

FIGS. 15A and 15B are perspective views showing a digital camera as onespecific example of electronic apparatus;

FIG. 16 is a perspective view showing a laptop personal computer as onespecific example of electronic apparatus;

FIG. 17 is a perspective view showing a video camera as one specificexample of electronic apparatus;

FIGS. 18A to 18G are diagrams showing a cellular phone as portableterminal apparatus as one specific example of electronic apparatus; and

FIG. 19 is an explanatory diagram showing one example of a manufacturingstep for an organic EL display in a related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Methods for manufacturing an organic EL display and organic EL displaysaccording to embodiments of the present invention will be describedbelow based on the drawings.

First Embodiment

Initially, the schematic structure of an organic EL display will bedescribed below.

FIG. 1 is a major-part sectional view showing one example of theschematic structure of the display area of the organic EL display. Inthis example, the schematic structure of an active-matrix organic ELdisplay in which organic EL elements are arranged as light-emittingelements is shown.

An organic EL display 1 of this example includes TFTs 4 in therespective pixels over a substrate 3. Over the substrate 3 on which theTFTs 4 are formed, interconnects 5 connected to the sources and drainsof the TFTs 4 are formed, and a planarization insulating film 7 isprovided to cover these interconnects 5. The TFT 4 is not limited to thebottom-gate TFT shown in FIG. 1 but may be a top-gate TFT. The gateelectrodes of the TFTs 4 are connected to a scan circuit.

In each of pixel apertures A over this planarization insulating film 7,an organic EL element 15 arising from stacking of a lower electrode 9,an organic layer 11, and an upper electrode 13 is provided. Inparticular, in the organic EL display 1 of the present embodiment, anauxiliary interconnect 9 a formed of the same layer as that of the lowerelectrode 9 is provided among the pixel apertures A in which the organicEL elements 15 are provided. The pixel apertures A are formed in aninsulating film 17 that covers the lower electrodes 9.

The lower electrode 9 of the organic EL element 15 is connected to theinterconnect 5 via a connection hole 7 a formed in the planarizationinsulating film 7, and is so formed as to have a pattern somewhat largerthan the pixel aperture A.

The auxiliary interconnect 9 a formed of the same layer as that of thelower electrodes 9 is continuously disposed in a mesh manner among thepixel apertures A arranged in a matrix over the substrate 3 for example,and is so patterned that insulation from the lower electrodes 9 is kept.

The peripheral edges of these lower electrodes 9 and the auxiliaryinterconnect 9 a are covered by the insulating film 17 through which thecenter parts of the lower electrodes 9 are exposed. The openings of theinsulating film 17 for exposing the center parts of the lower electrodes9 serve as the pixel apertures A. In the insulating film 17, connectionholes 17 a that reach the auxiliary interconnect 9 a are provided inaddition to the pixel apertures A. The connection holes 17 a areprovided at the positions according to need, and do not need to beprovided corresponding to each of the pixel apertures A.

The organic layer 11 is formed as a pattern for each of the pixelapertures A in such a manner as to cover the lower electrode 9 exposedin the pixel aperture A defined by the insulating film 17.

The upper electrode 13 is so provided as to completely cover the organiclayer 11 and be connected to the auxiliary interconnect 9 a via theconnection holes 17 a provided in the insulating film 17. This upperelectrode 13 may be provided as a blanket film above the substrate 3.Alternatively, for each of plural areas, it may be formed as patternseach shared by plural pixels.

Because the TFT 4 is formed in each of the pixels over the substrate 3in this organic EL display 1, it is advantageous for this organic ELdisplay 1 to have a top-emission structure that allows extraction ofemitted light through the upper electrode 13 on the opposite side to thesubstrate 3, in terms of ensuring of a high aperture ratio of theorganic EL elements. In the case of the top-emission display, thesubstrate 3 is not limited to a substrate composed of a transparentmaterial.

If the organic EL display 1 is a top-emission display, it is preferablefor the lower electrode 9 to be composed of a metal material havingfavorable light reflectivity, such as aluminum (Al), silver (Ag), asilver alloy composed mainly of silver (Ag), or chromium (Cr), so thatemitted light may be reflected toward the upper electrode 13. Inparticular, using silver (Ag) or a silver alloy is preferable because itcan reflect more emitted light.

Furthermore, in this case, a two-layer structure obtained by providingan electrically-conductive oxide material layer having opticaltransparency and excellent surface flatness on this metal material layermay be employed for the purpose of planarizing the surface of the lowerelectrode 9. This conductive oxide material layer serves also as abarrier layer for preventing oxidation of the metal material layerhaving favorable reflectivity, composed of e.g. silver (Ag) inparticular.

In addition, under the metal material layer, anotherelectrically-conductive oxide material layer serving as an adhesionlayer to the underlying planarization insulating film 7 may be provided,so that a three-layer structure obtained by interposing the metalmaterial layer between the conductive oxide material layers may beemployed.

The lower electrode 9 is used as the anode or cathode. Depending onwhether it is used as the anode or cathode, a material having a properwork function is selected and used therefor. For example, when the lowerelectrode 9 is used as the anode, as the uppermost layer in contact withthe organic layer 11, a layer composed of a material having a high workfunction is used as a hole injection layer. Thus, when the lowerelectrode 9 is formed by employing the above-described two-layerstructure or three-layer structure, a layer composed of an indium oxidesuch as indium tin oxide (ITO) or indium zinc oxide (IZO) having a highwork function and favorable optical transparency is used as theuppermost conductive oxide material layer. ITO or IZO is used also forthe conductive oxide material layer provided as the adhesion layerbetween the metal material layer and the planarization insulating film7.

Consequently, as the structure of the lower electrode 9 used as theanode and the auxiliary interconnect 9 a, a three-layer structureobtained by interposing a metal material layer composed of silver (Ag)between electrically-conductive oxide material layers composed of ITOcan be cited.

The organic layer 11 is formed of a multilayer structure including atleast a light-emitting layer, and arises from sequential stacking of ahole injection layer, light-emitting layer, electron transport layer,and electron injection layer in that order from the anode side, forexample. These layers are adequately selected so as to be stacked.

If this organic EL display 1 is a top-emission display, it is preferablefor the upper electrode 13 to be composed of a material having opticaltransparency and have a sufficiently-small thickness in order to achievefavorable light-extraction efficiency. If the lower electrode 9 is theanode, the upper electrode 13 is used as the cathode.

In contrast to the above description, if the organic EL display 1 is atransmissive display from which emitted light is extracted through thesubstrate 3, the substrate 3 and the lower electrodes 9 are formed byusing a material having optical transparency. On the other hand, theupper electrode 13 is formed by using a material having favorable lightreflectivity.

In the organic EL display 1 having the above-described structure, theauxiliary interconnect 9 a connected to the upper electrode 13 is notformed by using a special layer but is formed of the same layer as thatof the lower electrodes 9. Due to this feature, without complication ofthe layer structure of the organic EL display 1, the electric resistanceof the upper electrode 13 can be lowered through the connecting of theauxiliary interconnect 9 a thereto. Thus, for example, even when theorganic EL display 1 is a top-emission display that allows lightextraction through the upper electrode 13 and therefore the upperelectrode 13 is demanded to have optical transparency and hence asmaller thickness, it is possible to decrease the resistance of theupper electrode 13 to thereby prevent a voltage drop thereacross withoutcomplication of the layer structure. As a result, the display is allowedto keep favorable displaying characteristics.

Next, a description will be made below about one example of a method formanufacturing the organic EL display having the above-describedstructure and a specific example of the further-detailed structure ofthe organic EL display.

FIGS. 2A to 2F are explanatory diagrams showing one example ofmanufacturing steps for the organic EL display.

In the manufacturing of the organic EL display having theabove-described structure, as shown in FIG. 2A, initially the TFTs 4 andthe interconnects 5 connected to the sources and drains of the TFTs 4are formed over the substrate 3 formed of e.g. a glass substrate.

Subsequently, as shown in FIG. 2B, the planarization insulating film 7is so formed over the substrate 3 as to fill recesses and projectionsgenerated on the surface side of the substrate 3 due to the formation ofthe TFTs 4 and the interconnects 5. For the formation of theplanarization insulating film 7, for example, positive-typephotosensitive polyimide is applied over the substrate 3 byspin-coating, and then pattern exposure in which only the part above theinterconnects 5 is irradiated with exposure light by exposure apparatusis carried out, followed by development by puddle-system developingapparatus. Subsequently, main baking for imidizing (cyclizing) thepolyimide is carried out in a clean-bake furnace. This forms theplanarization insulating film 7 having the connection holes 7 a thatreach the interconnects 5. For example, this planarization insulatingfilm 7 is formed to have a thickness of about 2.0 μm if the recesses andprojections existing after the formation of the interconnects 5 have aheight difference of about 1.0 μm.

Referring next to FIG. 2C, the lower electrodes 9 and the auxiliaryinterconnect 9 a are formed on the planarization insulating film 7. Inthe present example, the lower electrodes 9 to serve as the anodes areformed. In this case, initially an electrically-conductive oxidematerial layer (composed of e.g. ITO) serving as an adhesion layer isdeposited by DC sputtering to a thickness of about 20 nm on theplanarization insulating film 7. Subsequently, a metal material (e.g.Ag) is deposited by DC sputtering to a thickness of about 100 nm.Thereafter, on this metal material layer, an electrically-conductiveoxide material layer (composed of e.g. ITO) serving as a barrier layer,hole injection layer, and planarization layer is deposited by DCsputtering to a thickness of about 10 nm.

The thickness of the conductive oxide material layer formed as theadhesion layer may be any as long as this layer allows adhesion. If thislayer is composed of ITO, it is formed to have a thickness in the rangeof 5 nm to 100 nm. The thickness of the metal material layer may be anyas long as this layer prevents emitted light from passing therethroughand can be processed. If this layer is composed of Ag, it is formed tohave a thickness in the range of 50 nm to 500 nm. The conductive oxidematerial layer serving as the barrier layer, hole injection layer, andplanarization layer is formed to have a thickness in the range of 3 nmto 50 nm, which corresponds to the limit of processing.

Subsequently, these metal material layer and conductive oxide materiallayers are patterned by etching in which a resist pattern formed by ageneral lithography technique is used as the mask. As a result, thelower electrodes 9 connected to the interconnects 5 via the connectionholes 7 a are arranged in a matrix corresponding to the respective pixelparts. Furthermore, the auxiliary interconnect 9 a is formed among theselower electrodes 9.

In the case of forming the lower electrodes 9 and the auxiliaryinterconnect 9 a having a two-layer structure, a metal material layer(composed of e.g. Ag) is deposited on the planarization insulating film7 to a thickness of about 150 nm by DC sputtering, and then an ITO layeris deposited thereon to a thickness of about 10 nm, followed bypatterning of these layers.

Thereafter, as shown in FIG. 2D, the insulating film 17 having the pixelapertures A and the connection holes 17 a is formed. For the formationof the insulating film 17, initially a silicon dioxide (SiO₂) film isdeposited by e.g. CVD to a thickness of about 1.0 μm. Thereafter, thesilicon dioxide film is patterned by etching in which a resist patternformed by a general lithography technique is used as the mask. Thisetching is carried out under the condition that allows the sidewallresulting from the etching to have a tapered shape. As a result, theinsulating film 17 is obtained that is formed of the silicon dioxidefilm and has the pixel apertures A that expose the center parts of thelower electrodes 9 and the connection holes 17 a that reach theauxiliary interconnect 9 a. This insulating film 17 is not limited to asilicon dioxide film.

Referring next to FIG. 2E, the organic layer 11 is formed as patternsthat each have a shape covering the lower electrode 9 exposed at thebottom of the pixel aperture A. For the formation of the organic layer11, evaporation deposition by use of a low-molecular organic material iscarried out in the state in which an evaporation mask 29 is disposed toface the insulating film 17 in the present example. This evaporationmask 29 has apertures 29 a corresponding to the formation part of theorganic layer 11. In order that the organic layer 11 is so formed as tosurely cover the lower electrode 9 in the pixel aperture A, theapertures 29 a are so designed that, in plan view from the evaporationmask side, the edge of each aperture 29 a overlaps with the sidewall ofthe insulating film 17 around the pixel aperture A so that the whole ofthe exposed part of the lower electrode 9 may be exposed through theaperture 29 a.

By the evaporation deposition with use of this evaporation mask 29, theorganic layer 11 is formed that is obtained by sequentially stacking,from the lower electrode 9 side, e.g.4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (MTDATA) as a holeinjection layer, bis(N-naphthyl)-N-phenylbenzidine (α-NPD) as a holetransport layer, and a 8-quinolinol aluminum complex (Alq3) as alight-emitting layer.

In the evaporation deposition, 0.2 g of each of the materials of theorganic layer 11 is loaded on a boat for resistive heating and each boatis attached to a predetermined electrode in vacuum evaporationapparatus. Subsequently, the pressure in the evaporation chamber isdecreased to about 0.1×10⁻⁴ Pa, and then voltage is sequentially appliedto the respective boats, to thereby sequentially deposit the pluralorganic materials by evaporation. The thicknesses of the respectivematerial layers are as follows: 30 nm for MTDATA as the hole injectionlayer, 20 nm for α-NPD as the hole transport layer, and 30 nm for Alq3as the light-emitting layer.

In the above-described evaporation deposition, the evaporation mask 29may be disposed on the insulating film 17 to keep a predetermineddistance between the evaporation mask 29 and the substrate 3.

After the above-described step, as shown in FIG. 2F, the upper electrode13 is formed that covers the organic layers 11 and the insulating film17 and is connected to the auxiliary interconnect 9 a via the connectionholes 17 a in the insulating film 17. In the present example, an Mg—Agfilm to serve as the cathode is formed by co-evaporation across theentire surface over the substrate 3.

For the formation of the upper electrode 13, 0.1 g of Mg and 0.4 g of Agare loaded on the respective boats and each boat is attached to apredetermined electrode in vacuum evaporation apparatus. Subsequently,the pressure in the evaporation chamber is decreased to about 0.1×10⁻⁴Pa, and then voltage is applied to the respective boats, to therebycarry out the co-evaporation of Mg and Ag above the substrate 3. As oneexample, the ratio of the deposition rate of Mg to that of Ag is set toabout 9 to 1, and the Mg—Ag film is formed to a thickness of about 10nm.

The formation of the organic layer 11 and that of the upper electrode13, both of which are carried out by evaporation deposition, arecontinuously carried out in the same evaporation chamber. However, afterthe end of the evaporation deposition of the organic layer 11 and beforethe evaporation deposition of the upper electrode 13, the evaporationmask 29 is removed from the substrate 3.

Through the above-described steps, the organic EL display 1 having thestructure described with FIG. 1 is obtained.

In the above-described manufacturing method, as described with FIG. 2C,the auxiliary interconnect 9 a is formed in the same step as that of theformation of the lower electrodes 9. Furthermore, as described with FIG.2D, the connection holes 17 a that reach the auxiliary interconnect 9 aare formed in the same step as that of the formation of the pixelapertures A in the insulating film 17. In addition, as described withFIGS. 2F and 1, the upper electrode 13 is so formed as to cover theorganic layers 11 and be connected to the auxiliary interconnect 9 a viathe connection holes 17 a. Therefore, without step addition, the organicEL display in which the auxiliary interconnect 9 a is connected to theupper electrode 13, i.e., the organic EL display 1 described with FIG.1, can be achieved.

This makes it possible to suppress the manufacturing cost of the organicEL display in which the auxiliary interconnect 9 a is connected to theupper electrode 13, and to achieve yield enhancement through reductionin the number of manufacturing steps.

FIG. 3 is a perspective view showing a schematic configuration exampleof the organic EL display 1 obtained through the above-describedprocedure.

As shown in this example, the planar area on the substrate 3 of theorganic EL display 1 is composed of a light-emission area 21 and aperipheral area 22 thereof.

In the light-emission area 21, the organic EL elements 15 arising fromstacking of the lower electrode 9, the organic layer 11, and the upperelectrode 13 are arranged in a matrix. Specifically, the light-emissionarea 21 is composed of plural pixel areas, and the organic EL element 15is formed in each of the pixel areas.

In the peripheral area 22, peripheral circuits 22 a for driving theorganic EL elements 15 in the respective pixel areas and electrodeterminals 22 b for inputting power, signals, and so on are formed. Theelectrode terminal 22 b is obtained by exposing a metal layer(interconnect 5).

Such an organic EL display 1 is completed through so-called scribetreatment. Specifically, the respective layers are deposited over thesubstrate 3 having a size including an area 23 positioned on the outerside of the peripheral area 22 (hereinafter, referred to as an“outer-peripheral area”). After the completion of the deposition of allthe layers, the outer-peripheral area 23 is removed by cutting by scribetreatment and only an effective area 24 composed of the light-emissionarea 21 and the peripheral area 22 is left, so that the organic ELdisplay 1 is completed.

In the manufacturing process for the organic EL display based on theabove-described procedure, after the step of forming the organic ELelements arising from the stacking of the lower electrode 9, the organiclayer 11, and the upper electrode 13 and before the step of removing theouter-peripheral area 23 outside the effective area 24 by scribetreatment to thereby leave only the effective area 24, a silicon nitride(SiN) film or a silicon dioxide (SiO₂) film covering the entiresubstrate including the organic EL elements is often formed as aprotective film for protecting the entire substrate by CVD depositiontreatment involving electrification. However, if the manufacturingprocess includes such a step of forming a protective film, a part thatlooks white turbidity is possibly generated in the vicinity of the outerperiphery of the light-emission area attributed to an electrificationcharge generated in plasma treatment used in the CVD deposition step.

To avoid this problem, the method for manufacturing an organic ELdisplay according to the present embodiment goes through the followingcharacteristic procedure.

FIG. 4 is an explanatory diagram showing one example of a manufacturingstep for an organic EL display according to the present embodiment.

As shown in this example, in the manufacturing of the organic ELdisplay, a metal layer (composed of e.g. a TiAl-based alloy) serving asthe interconnect 5 is deposited as a pattern on the substrate 3, and theplanarization insulating film 7 is deposited thereon. Furthermore, theauxiliary interconnect 9 a is formed, and the insulating film 17 isformed on the top surface side of the auxiliary interconnect 9 a.Moreover, a protective film 10 for protecting the entire substrate isdeposited by CVD to cover the whole of the top surface side of theselayers.

However, as described above, the protective film 10 deposited by CVDwill be charged due to plasma treatment. Such charging should besuppressed because it possibly causes the occurrence of film rougheningon the surface of the CVD film and hence white turbidity in theeffective area 24.

To suppress the charging, in the method for manufacturing an organic ELdisplay according to the present embodiment, at the time of thedeposition of the metal layer serving as the interconnect 5 before thedeposition treatment for the protective film 10 by CVD, the metal layeris formed not only in the effective area 24 but also in theouter-peripheral area 23. Furthermore, a protective electrode 25 forelectrically connecting the metal layer in the peripheral area 22 to themetal layer formed in the outer-peripheral area 23 (hereinafter, thismetal layer will be referred to as an “outer-peripheral electrode”) isformed. Specifically, in general, the metal layer pattern is depositedin such a way that the metal layer is discontinued at the boundarybetween the effective area 24 and the outer-peripheral area 23 (alongthe cut line in FIG. 4) in consideration of easiness of the subsequentscribe treatment. In contrast, in the present embodiment, the protectiveelectrode 25 is formed by depositing the metal layer pattern in such away that a metal portion connected to the metal layer in the peripheralarea 22 and the outer-peripheral electrode across the boundary exists.

The number, positions, and so on of the protective electrodes 25 are notparticularly limited as long as at least one protective electrode 25 isformed per one effective area 24.

FIGS. 5A to 5C are explanatory diagrams showing specific examples of theformation positions of the protective electrodes 25.

When the light-emission area 21 has a rectangular shape, white turbidityin the light-emission area 21 tends to be frequently generated near therespective vertexes of the rectangular shape. Therefore, it will beeffective that the protective electrodes 25 are formed near therespective vertexes of the light-emission area 21 as shown in FIG. 5A.

In the case of forming plural organic EL displays 1 on one substrate 3,i.e., carrying out so-called multi-panel cutting, it will be possiblethat, as shown in FIG. 5B, the protective electrodes 25 are formed onlyat positions adjacent to the outer-peripheral area 23 (in the example ofFIG. 5B, two positions on the left side of an effective area 24 a andtwo positions on the right side of an effective area 24 b).

Furthermore, in the case of carrying out multi-panel cutting, it will bealso possible that, as shown in FIG. 5C, the outer-peripheral area 23 isprovided also between the effective areas 24 in the substrate accordingto need and the protective electrodes 25 connected to thisouter-peripheral area 23 are formed.

Such a protective electrode 25 is to electrically connect a metal layerin the peripheral area 22 to an outer-peripheral electrode. The metallayer in the peripheral area 22 is electrically connected to theauxiliary interconnect 9 a, and the electric connection of the auxiliaryinterconnect 9 a to the lower electrode 9 or the upper electrode 13 ofthe organic EL element 15 in each pixel area is ensured. That is, themetal layer in the peripheral area 22 and the auxiliary interconnect 9 afunction as a common electrode for ensuring the electric connection toeach pixel area.

Consequently, the protective electrode 25 electrically connects theouter-peripheral electrode to the common electrode for ensuring theelectric connection to each pixel area, to thereby generate a chargeflow from the common electrode to the outer-peripheral electrode.

In the manufacturing method that goes through the above-describedcharacteristic procedure and the organic EL display 1 obtained throughthis procedure, the protective electrode 25 is formed before CVDdeposition treatment involving electrification. Therefore, even when theCVD film (protective film 10) is charged in the CVD depositiontreatment, the electrification charge flows from an electrode terminalin the peripheral area 22 to an outer-peripheral electrode due to acharge flow generated by the protective electrode 25. That is, a problemthat the electrification charge accumulates at a certain position in theeffective area 24 does not occur.

Consequently, if the manufacturing goes through the above-describedcharacteristic procedure, the electrification charge will not accumulateat a certain position in the effective area 24. Thus, even if filmdeposition treatment involving electrification such as CVD deposition byuse of plasma treatment is carried out in the manufacturing process forthe organic EL display 1, it is possible to suppress generation of whiteturbidity at a certain position in the effective area 24 attributed tothe electrification charge generated in the film deposition treatment.That is, the organic EL display 1 free from the generation of whiteturbidity can be manufactured, which allows enhancement in themanufacturing quality, manufacturing yield, and so forth. Moreover, thecharge flow generated by the protective electrode 25 can avoid electricdamage to electric circuits such as the TFTs 4 included in the organicEL display.

Second Embodiment

FIG. 6 is an explanatory diagram showing another example of amanufacturing step for an organic EL display according to a secondembodiment of the present invention.

In the manufacturing of the organic EL display of this example, a metallayer (composed of e.g. a TiAl-based alloy) serving as the interconnect5 is deposited as a pattern on the substrate 3, and the planarizationinsulating film 7 is deposited thereon. Furthermore, the auxiliaryinterconnect 9 a is formed, and the upper electrode 13 is formed on thetop surface side of the auxiliary interconnect 9 a with the intermediaryof the insulating film 17. It will be possible that the upper electrode13 is formed of e.g. a blanket film of magnesium-silver (MgAg).Moreover, the protective film 10 for protecting the entire substrate isdeposited by CVD to cover the whole of the top surface side of theselayers.

However, the protective film 10 deposited by CVD will be charged due toplasma treatment. Such charging should be suppressed because it possiblycauses the occurrence of film roughening on the surface of the CVD filmand hence white turbidity in the effective area 24.

To suppress the charging, also in the present embodiment, similarly tothe above-described first embodiment, at the time of the deposition ofthe metal layer serving as the interconnect 5 before the depositiontreatment for the protective film 10 by CVD, the metal layer is formednot only in the effective area 24 but also in the outer-peripheral area23. Furthermore, the protective electrode 25 for electrically connectingthe metal layer in the peripheral area 22 to the outer-peripheralelectrode is formed.

Such a protective electrode 25 is to electrically connect the metallayer in the peripheral area 22 to the outer-peripheral electrode. Themetal layer in the peripheral area 22 is electrically connected to theauxiliary interconnect 9 a, and the electric connection of the auxiliaryinterconnect 9 a to the upper electrode 13 formed of a blanket film isensured. That is, the metal layer in the peripheral area 22, theauxiliary interconnect 9 a, and the upper electrode 13 function as acommon electrode for ensuring the electric connection to each pixelarea.

Consequently, the protective electrode 25 electrically connects theouter-peripheral electrode to the common electrode for ensuring theelectric connection to each pixel area, to thereby generate a chargeflow from the common electrode to the outer-peripheral electrode.

Specifically, also in the present embodiment, the protective electrode25 is formed before CVD deposition treatment involving electrificationsimilarly to the above-described first embodiment. Therefore, even whenthe CVD film (protective film 10) is charged in the CVD depositiontreatment, the electrification charge flows from an electrode terminalin the peripheral area 22 to the outer-peripheral electrode due to acharge flow generated by the protective electrode 25. That is, a problemthat the electrification charge accumulates at a certain position in theeffective area 24 does not occur. Consequently, even if film depositiontreatment involving electrification such as CVD deposition by use ofplasma treatment is carried out in the manufacturing process for theorganic EL display 1, it is possible to suppress generation of whiteturbidity at a certain position in the effective area 24 attributed tothe electrification charge generated in the film deposition treatment.That is, the organic EL display 1 free from the generation of whiteturbidity can be manufactured, which allows enhancement in themanufacturing quality, manufacturing yield, and so forth. Moreover, thecharge flow generated by the protective electrode 25 can avoid electricdamage to electric circuits such as the TFTs 4 included in the organicEL display.

In particular, in the present embodiment, the upper electrode 13 formedof a blanket film functions as a part of the common electrode.

FIG. 7 is a perspective view showing a schematic configuration exampleof the organic EL display 1 according to the present embodiment.

In such an organic EL display 1, the upper electrode 13 covers the wholeof the respective pixel areas because it is formed of a blanket film.Thus, the upper electrode 13 electrically shields electric circuits (TFTcircuits, pixel circuits, peripheral circuits, and so on) formed belowthe upper electrode 13. Consequently, by allowing the upper electrode 13to function as a part of the common electrode, electric damage to theelectric circuits can be surely prevented and thus the electric circuitscan be protected in CVD deposition treatment. Furthermore, it is alsopossible to surely transfer the electrification charge of the CVD filmto the outer-peripheral electrode. That is, this configuration will bethe most effective in terms of prevention of white turbidity in the CVDfilm and protection of electric circuits such as the TFTs 4.

Third Embodiment

FIG. 8 is a major-part sectional view showing another example of theschematic structure of the display area of an organic EL display.

In the organic EL display of this example, a multilayer structure 30obtained by sequentially stacking a cathode auxiliary interconnect 31,an interlayer insulating film 32, a source metal layer 33, aplanarization film 34, an ITO layer 35, and a bank layer 36 is formed onthe substrate 3. This multilayer structure 30 is formed on thelight-emission area 21. A cathode 37 is deposited on the multilayerstructure 30. The interlayer insulating film 32 electrically isolatesdata lines Idat and scan lines Vsel from the cathode auxiliaryinterconnect 31. On the interlayer insulating film 32, the source metallayer 33 patterned in the same step as that for the data lines Idat andthe scan lines Vsel is formed into an island shape. The source metallayer 33 is electrically connected to the cathode auxiliary interconnect31 via contact holes h5 opened in the interlayer insulating film 32. Theinsulating planarization film 34 subjected to planarization treatment isstacked on the interlayer insulating film 32, and the ITO layer 35patterned into an island shape is formed on the planarization film 34.The ITO layer 35 is electrically connected to the source metal layer 33via contact holes h3 opened in the planarization film 34. The pluralcontact holes h3 are opened along the extension direction of the cathodeauxiliary interconnect 31. By providing a large number of contactsbetween the ITO layer 35 and the source metal layer 33, the electricresistance is decreased.

Also in the case of the organic EL display having such a structure, if aprotective film (not shown) for protecting the entire substrate isdeposited by CVD after the deposition of the respective layers over thesubstrate 3, the protective film formed by the film deposition treatmentwill be charged due to plasma treatment used in the film deposition. Tosuppress the charging, also in the present embodiment, similarly to theabove-described first and second embodiments, at the time of thedeposition of the metal layer serving as the cathode auxiliaryinterconnect 31 before the deposition treatment for the protective filmby CVD, the metal layer is formed not only in the effective area 24 butalso in the outer-peripheral area 23. Furthermore, the protectiveelectrode 25 for electrically connecting the metal layer in theperipheral area 22 to the metal layer formed in the outer-peripheralarea 23 (outer-peripheral electrode) to thereby generate a charge flowis formed.

In the present embodiment, the metal layer in the effective area 24 isuniformly deposited on the substrate 3 as a so-called blanket film, andthe cathode auxiliary interconnect 31 is formed by this metal layer.Therefore, via the cathode auxiliary interconnect 31, the electricconnection to the lower electrode 9 or the upper electrode 13 of theorganic EL element 15 in each pixel area is ensured. That is, the metallayer formed in the peripheral area 22 and the cathode auxiliaryinterconnect 31 electrically connected to the metal layer function as acommon electrode for ensuring the electric connection to each pixelarea.

Also in the present embodiment, similarly to the above-described firstand second embodiments, even when the CVD film is charged in CVDdeposition treatment, the charge flow generated by the protectiveelectrode 25 prevents the occurrence of accumulation of theelectrification charge at a certain position in the effective area 24.Consequently, even if film deposition treatment involvingelectrification such as CVD deposition by use of plasma treatment iscarried out in the manufacturing process for the organic EL display 1,it is possible to suppress generation of white turbidity at a certainposition in the effective area 24 attributed to the electrificationcharge generated in the film deposition treatment. Moreover, the chargeflow generated by the protective electrode 25 can avoid electric damageto electric circuits such as the TFTs 4 included in the organic ELdisplay. That is, the manufacturing quality, manufacturing yield, and soon of the organic EL display 1 can be enhanced.

Fourth Embodiment

FIG. 9 is a circuit diagram schematically showing a specific example ofinterconnects (mainly, interconnects connected to pixel circuits) in theeffective area 24 of an organic EL display. As shown in this example,substantially all of the interconnects (signal lines, power supplylines, and so on) connected to the pixel circuits arranged correspondingto the respective pixel areas in the light-emission area 21 are soprovided as to range across the whole of the effective area 24 exceptthe peripheral area 22. Therefore, any of these interconnects can beused as a common electrode for ensuring the electric connection to eachpixel area.

FIG. 10 is a circuit diagram schematically showing a connection examplein which an upper-electrode interconnect is used as a common electrode.The upper-electrode interconnect is to ensure the electric connection toeach pixel area via the metal layer in the peripheral area 22, theauxiliary interconnect 9 a, and the upper electrode 13 as describedabove for the second embodiment. Because only the circuit connectionstate is shown in this example, this diagram is made as if theupper-electrode interconnect is distributed only in the pixel areas.However, the actual upper-electrode interconnect is so distributed as tocover the whole of the effective area 24.

For this circuit arrangement, it will be possible to dispose theprotective electrode 25 for electrically connecting an outer-peripheralelectrode to an electrode terminal Vcat connected to the upper-electrodeinterconnect between the outer-peripheral electrode and the electrodeterminal Vcat to thereby allow generation of a charge flow from theelectrode terminal Vcat to the outer-peripheral electrode.

If such a circuit arrangement (electric connection form) is realized,the upper electrode 13 electrically shields the whole of thelight-emission area 21, and the charge can be transferred to theouter-peripheral electrode via the protective electrode 25. Thus, thiscircuit arrangement will be the most effective in terms of prevention ofwhite turbidity in a CVD film and protection of electric circuits suchas the TFTs 4.

FIG. 11 is a circuit diagram schematically showing a modificationexample in which the upper-electrode interconnect is used as a commonelectrode. This diagram shows a connection example in which theconnection between the upper-electrode interconnect and anouter-peripheral electrode is made at a position other than the vicinityof the electrode terminal Vcat connected to the upper-electrodeinterconnect. That is, the protective electrode 25 may be provided atany position as long as it connects the common electrode to anouter-peripheral electrode. Therefore, it may be provided at a positionother than the vicinity of the electrode terminal Vcat like thisexample.

FIG. 12 is a circuit diagram schematically showing a connection examplein which a power supply line is used as a common electrode. This diagramshows an example in which the protective electrode 25 is providedbetween an outer-peripheral electrode and an electrode terminal Vsubconnected to the power supply line. Also when the power supply line isthus utilized, the electric connection to the pixel circuits arrangedcorresponding to the respective pixel areas can be ensured, and thus thecharge can be transferred to the outer-peripheral electrode via theprotective electrode 25.

FIG. 13 is a circuit diagram schematically showing a connection examplein which signal lines are used as a common electrode. When the signallines are used as a common electrode, the whole of the effective area 24is not covered by one signal line. Therefore, as shown in this example,the electric connection to an outer-peripheral electrode via theprotective electrode 25 should be ensured for each of electrodeterminals Sig(1) to Sig(3) corresponding to the respective signal lines.Also when the signal lines are thus utilized, providing the protectiveelectrodes 25 corresponding to the respective signal lines allowsensuring of the electric connection to the respective pixel circuits,and thus permits the charge to be transferred to the outer-peripheralelectrode via the protective electrodes 25.

Fifth Embodiment

The organic EL display 1 obtained based on the above-describedembodiments can be used as a display in various kinds of electronicapparatus shown in FIGS. 14 to 18. Specifically, it can be used as adisplay in electronic apparatus in any field that displays an image orvideo based on a video signal input thereto or produced therein, such asa digital camera, laptop personal computer, portable terminal apparatustypified by a cellular phone, and video camera. Specific examples ofelectronic apparatus in which the organic EL display is used will bedescribed below.

The organic EL display also encompasses a module-shape display with asealed structure. Examples of such a display include a display moduleformed by attaching a counter part composed of e.g. transparent glass toa pixel array part. This transparent counter part may be provided with acolor filer, protective film, light-shielding film, and so on. Thisdisplay module may be provided with a circuit part, flexible printedcircuit (FPC), and so on for inputting/outputting of signals and soforth to/from the pixel array part from/to the external.

FIG. 14 is a perspective view showing a television as one specificexample of the electronic apparatus. This television includes a videodisplay screen 101 composed of a front panel 102, a filter glass 103,and so on, and is fabricated by using the organic EL display as thevideo display screen 101.

FIGS. 15A and 15B are perspective views showing a digital camera as onespecific example of the electronic apparatus: FIG. 15A is a front-sideview and FIG. 15B is a rear-side view. This digital camera includes alight emitter 111 for flash, a display part 112, a menu switch 113, ashutter button 114, and so on, and is fabricated by using the organic ELdisplay as the display part 112.

FIG. 16 is a perspective view showing a laptop personal computer as onespecific example of the electronic apparatus. This laptop personalcomputer includes in a main body 121 thereof a keyboard 122 operated ininputting of characters and so forth, and a display part 123 fordisplaying images. The laptop personal computer is fabricated by usingthe organic EL display as the display part 123.

FIG. 17 is a perspective view showing a video camera as one specificexample of the electronic apparatus. This video camera includes a mainbody 131, a lens 132 that is disposed on the front side of the cameraand used to capture a subject image, a start/stop switch 133 for imagingoperation and a display part 134. The video camera is fabricated byusing the organic EL display as the display part 134.

FIGS. 18A to 18G are diagrams showing a cellular phone as portableterminal apparatus as one specific example of the electronic apparatus:FIGS. 18A and 18B are front view and side view, respectively, of theopened state, and FIG. 18C to 18G are front view, left-side view,right-side view, top view, and bottom view, respectively, of the closedstate. This cellular phone includes an upper casing 141, a lower casing142, a connection (hinge) 143, a display 144, a sub-display 145, apicture light 146 and a camera 147. The cellular phone is fabricated byusing the organic EL display as the display 144 and the sub-display 145.

In the above description of the first to fifth embodiments, specificexamples of preferred embodiments of the present invention areexplained. However, the present invention is not limited thereto but canbe properly changed without departing the gist thereof. For example, thematerials, thicknesses, deposition methods, deposition conditions, andso on of the respective components cited as examples for the embodimentsare not particularly limited but can be properly changed according toneed.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factor in so far as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method for manufacturing an organicelectroluminescence display including a plurality of pixel areas, themethod comprising the steps of: forming a multilayer structure for eachpixel area in an effective area of a substrate, the multilayer structureincluding (1) a lower electrode, (2) an organic layer, and (3) an upperelectrode; electrically connecting the pixel areas with a commonelectrode; forming a protective electrode for electrically connectingthe common electrode to an outer-peripheral electrode in an area that isoutside of the effective area, the protective electrode being continuousacross the boundary between the outer-peripheral electrode and theeffective area and effective to generate a charge flow from the commonelectrode to the outer-peripheral; and forming an insulating layer overthe substrate while allowing charges generated by the formation of theinsulating to discharge to an area outside of the substrate therefromvia the protective electrode.
 2. The method for manufacturing theorganic electroluminescence display according to claim 1, wherein thecommon electrode includes an auxiliary interconnect in the same layer asthe lower electrode.
 3. The method for manufacturing the organicelectroluminescence display according to claim 1, wherein the commonelectrode includes the upper electrode, and the upper electrode coversthe pixel areas.
 4. A method for manufacturing an organicelectroluminescence display comprising the steps of: forming organicelectroluminescence elements each having a multilayer structure for eachpixel area in an effective area of a substrate, the multilayer structureincluding (1) a lower electrode, (2) an organic layer, and (3) an upperelectrode; electrically connecting the pixel areas with a commonelectrode; and removing an area of the electroluminescence elements thatis outside of the effective area, wherein, after the step of forming theorganic electroluminescence elements and before the step of removing anarea of the electroluminescence elements that is outside of theeffective area, an insulating protective film is formed over thesubstrate and the organic electroluminescence elements by a filmdeposition treatment involving electrification, and a protectiveelectrode for electrically connecting the common electrode to anouter-peripheral electrode is formed in the area that is outside of theeffective area, the protective electrode being continuous across theboundary between the outer-peripheral electrode and the effective areaand effective to generate a charge flow from the common electrode to theouter-peripheral electrode in the film deposition treatment for theprotective film and allowing charges generated in the insulatingprotective layer during the formation of the insulating protective layerto discharge to an area outside of the substrate during the formation ofthe insulating protective layer.
 5. The method for manufacturing theorganic electroluminescence display according to claim 1, wherein theinsulating protective film is made from silicon nitride or silicondioxide.
 6. The method for manufacturing the organic electroluminescencedisplay according to claim 1, wherein the insulating protective filmcovers the entire top surface of the substrate.
 7. The method of claim1, wherein said charges are removed from said insulating film by meansof a protective electrode.
 8. The method of claim 1, wherein, theorganic electroluminescent display includes a drive circuit configuredto drive each pixel located in the pixel areas via an electric path, andthe electric path is independent of the drive circuit.
 9. The method ofclaim 8, further comprising the step of: disconnecting the electric pathfrom the substrate after the step of forming the insulating layer. 10.The method of claim 8, further comprising the step of attachingcircuitry configured to provide an image signal to the organicelectroluminescence display, wherein the organic electroluminescencedisplay is suitable for an electronic device selected from a groupconsisting of a television, a digital camera, a portable computer, amobile phone, and a video camera.
 11. The method of claim 1, wherein thestep of forming the insulating layer includes plasma generation via aCVD deposition treatment process.
 12. The method of claim 4, wherein theorganic electroluminescent display includes a drive circuit configuredto drive each pixel located in the pixel areas via an electric path, andthe electric path is independent of the drive circuit.
 13. The method ofclaim 12, further comprising the step of disconnecting the electric pathfrom the substrate after the step of forming the insulating layer. 14.The method of claim 4, wherein the step of forming the insulating layerincludes plasma generation via a CVD deposition treatment process.